Test Tube Babies Not at Higher Cancer Risk

Action Points

Note that this study was published as an abstract and presented at a conference. These data and conclusions should be considered to be preliminary until published in a peer-reviewed journal.

Note that this large, English registry study demonstrated no relationship between assisted conception and subsequent cancer rates in children.

Be aware that the increased risk of certain rare cancers may be due to statistical "noise" but will need to be evaluated in future studies.

Children born via assisted reproductive technologies weren't at an increased risk of cancer compared with the general population, though they may be more vulnerable to certain types of rare cancers, researchers found.

In a study of more than 100,000 children born through assisted conception in England between 1992 and 2008, there were 108 cancers found during follow-up compared with an expected 109.7, suggesting no increased risk of cancer, according to Carrie Williams, MD, of University College London, and colleagues.

But there was a significantly increased risk of hepatoblastoma and rhabdomyosarcoma, although these were based on small numbers and the absolute excess risks were small, the researchers reported at the European Society on Human Reproduction and Embryology meeting in London.

"It is true that we found increased risks of a few rare cancers, but these would need to be studied across large international datasets to confirm if they were genuine findings or just an effect of their very rareness," co-author Alastair Sutcliffe, MD, also of University College London, said in a statement.

Researchers have long questioned whether children born via assisted reproductive technologies are at greater risk of childhood cancer. Earlier studies have turned up mixed results: a recent meta-analysis found a moderately increased risk of childhood cancers in these patients, but Williams and colleagues noted that a recent population-based study with more than 26,000 participants found only a small though significantly increased cancer risk compared with spontaneously conceived children.

For their study, Williams and colleagues looked at data on 106,013 children tracked in the Human Fertilization & Embryology Authority (HFEA), and matched subsequent cancer cases via the U.K. National Registry of Childhood Tumors (NRCT).

Although the number of cancers they found was no more than would be expected in the general population, significantly more children developed hepatic tumors than expected (6 cases versus 1.83), which translated to more than a three-fold increased risk of the cancer in this population (SIR 3.27, 95% CI 1.20-7.12, P=0.029).

Williams and colleagues also found that significantly more children were diagnosed with rhabdomyosarcoma than expected (10 cases versus 3.81), which translated to more than a two-fold increased risk (SIR 2.62, 95% CI 1.26-4.82, P=0.016).

None of the children born via assisted reproductive technologies who developed cancer were recorded as having comorbidities consistent with an imprinting disorder, the researchers noted.

The study was limited by an inability to adjust for all potential mediating factors, but Williams and colleagues said the findings were "reassuring news for couples considering assisted conception, their subsequent children, fertility specialists and the wider public health."

They added that the "weaker evidence" of increased risks of the two rare cancers needs further exploration in larger studies and "may warrant further investigation into epigenetic aberrations associated with assisted reproduction."

The study was funded by Cancer Research UK, and a co-author was supported by the National Institute of Health Research.

The researchers reported no conflicts of interest.

Reviewed by F. Perry Wilson, MD, MSCE Instructor of Medicine, Perelman School of Medicine at the University of Pennsylvania and Dorothy Caputo, MA, BSN, RN, Nurse Planner

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